The anterior ocular segment in patients with diabetes mellitus seems to respond poorly to the stress of intra-ocular surgery. The reasons for this are not well understood at the present time; however, a review of the literature and our preliminary work have indicated abnormalities of corneal epithelium, corneal endothelium, tear secretion, corneal sensation and the structure of basement membranes and iris blood vessels. This study will attempt to: 1) arrive at a better understanding of these changes in the anterior ocular segment, 2) identify the role of surgical stress in the development of these changes, and 3) formulate better modes of the management of the diabetic patient to minimize these effects. To do this we propose to evaluate a sample of diabetic and control patients with the following anterior segment examinations; corneal aesthesiometry, Trigeminal Nerve conduction velocities, in vivo specular microscopy, corneal biomicroscopy and pachymetry, iris fluorescein angiography, ocular cultures and tests of lacrimal function. The same tests will be applied to a group of diabetics and controls undergoing intra-ocular surgery. The results will be correlated with histocompatibility antigens, hemoglobin A-IC concentrations and other concentrations and other systemic parameters. In addition, donor eyes from diabetics will be evaluated by electron and light microscopy for abnormalities, particularly of the corneal epithelium, endothelium and basement membranes.